20857949 has 8 divisors (see below), whose sum is σ = 23924160. Its totient is φ = 17813376.

The previous prime is 20857943. The next prime is 20857957. The reversal of 20857949 is 94975802.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20857949 - 2⁴ = 20857933 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20857943) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3284 + ... + 7245.

It is an arithmetic number, because the mean of its divisors is an integer number (2990520).

Almost surely, 2^20857949 is an apocalyptic number.

It is an amenable number.

20857949 is a deficient number, since it is larger than the sum of its proper divisors (3066211).

20857949 is a wasteful number, since it uses less digits than its factorization.

20857949 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10819.

The product of its (nonzero) digits is 181440, while the sum is 44.

The square root of 20857949 is about 4567.0503610098. The cubic root of 20857949 is about 275.2689336074.

The spelling of 20857949 in words is "twenty million, eight hundred fifty-seven thousand, nine hundred forty-nine".